Substrate processing apparatus and substrate processing method

ABSTRACT

A substrate processing apparatus comprising a substrate holding rotating mechanism, a process liquid supply mechanism having a nozzle for dispensing a process liquid toward a principal face of the substrate, a processing liquid reservoir for holding sufficient process liquid to form a liquid film covering the whole principal face of the substrate, a liquid film forming unit for forming the liquid film by supplying the process liquid onto the principal face of the substrate in a single burst, and a control unit for controlling the liquid film forming unit and the process liquid supply mechanism such that the process liquid is dispensed from the process liquid nozzle toward the principal face of the substrate after formation of the liquid film covering the whole area of the principal face of the substrate by the liquid film forming unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a substrate processing apparatus and asubstrate processing method for processing a substrate with a processliquid. Examples of substrates to be processed include semiconductorwafers, glass substrates for liquid crystal displays, glass substratesfor plasma displays, substrates for FEDs (field emission displays),substrates for optical discs, substrates for magnet-optical discs, glasssubstrates for photomasks, substrates for ceramics, substrates for solarcells, etc.

2. Description of Related Art

JP-A-2009-147038 discloses a substrate processing apparatus whichcomprises a spin chuck that holds a substrate in a horizontal positionand rotate the substrate, a chemical liquid dispense nozzle fordispensing a chemical liquid onto the substrate held by the spin chuck,and a rinsing liquid dispense nozzle for dispensing a rinsing liquidonto the substrate which already have been processed by chemical liquid.The chemical liquid dispense nozzle is connected via a chemical liquidvalve with a chemical liquid supply unit which is so configured as todynamically vary flow rates of the chemical liquid.

With this configuration, the following steps are performed: a first stepfor supplying the chemical liquid from the chemical liquid dispensenozzle toward a surface of the substrate at a first flow rate while thesubstrate being rotated by the spin chuck at a first rotational speed; asecond step for decreasing the substrate rotational speed into a secondrotational speed that is slower than the first rotational speed whilemaintaining the flow rate of the chemical liquid; and a third step fordecreasing a flow rate of chemical dispense liquid into a second flowrate while maintaining the substrate rotational speed at the secondrotational speed. In the first step, the whole surface of the substrateis being covered with the chemical. In the second step, a heap of thechemical liquid is being formed. In the third step, newly providedchemical liquid is being supplied onto the heap.

The chemical supply unit described in JP-A-147038 has a configuration soas to be able to dynamically change flow rate of chemical liquid. But inorder to do so, the chemical supply unit must be provided with a flowcontrol valve; which is expensive and responsible for a considerableincrease of overall costs.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide asubstrate processing apparatus and a substrate processing method whichcan rapidly form a liquid film covering the whole of a principal face ofa substrate, while keeping costs from increasing, thereby improvingqualities of substrate processing.

A preferred embodiment of the present invention provides a substrateprocessing apparatus comprising: a substrate holding rotating mechanismfor holding and rotating a substrate; a process liquid supply mechanismhaving a process liquid nozzle for dispensing a process liquid (inparticular, a chemical liquid) toward a principal face of the substrateheld by the substrate holding rotating mechanism; a process liquidreservoir for reserving a process liquid (preferably the same kind ofprocess liquid as the process liquid supplied from the process liquidnozzle) in an amount sufficient to form a liquid film covering the wholearea of the principal face of the substrate; a liquid film forming unitfor forming a liquid film covering the whole area of the principal faceof the substrate by supplying the process liquid reserved in the processliquid reservoir to the principal face of the substrate in a singleburst; and a control unit for dispensing a process liquid, after formingof the liquid film covering the whole area of the principal face of thesubstrate, toward the principal face of the substrate that is coveredwith the liquid film.

With this configuration, a liquid film covering the whole of area of aprincipal face of a substrate can be instantly formed to deliver aprocess liquid throughout the whole area of the principal area of thesubstrate, by supplying the process liquid reserved in a process liquidreservoir in a single burst while rotating the substrate with thesubstrate holding rotating mechanism, thereby enabling simultaneousprocessing with process liquids throughout the principal surface of thesubstrate. Thereafter, the process liquid is substituted with a newlyadded process liquid throughout the principal face of the substrate bydischarging (in a much smaller amount of flow volume) a new processliquid toward the principal face of the substrate via the process liquidnozzle and rotating the substrate with the substrate holding rotatingmechanism. In this case, the amount of process liquids consumption canbe kept low, thanks to the small amount of flow volume of the newlydischarged process liquid.

The present invention enables a formation of a liquid film covering thewhole area of the principal surface of the substrate, without employingexpensive components such as flow control valves, by adopting aconfiguration wherein a process liquid reserved in a processingreservoir is supplied in a single burst to a principal face of asubstrate. After the whole area of the principal face of the substrateis covered with the process liquid, only a small amount of flow volumeof a process liquid is required to be supplied, thus allowing a decreasein costs by keeping the amount of process liquids consumption low, whilewithout damaging uniformity of processing on the principal face of thesubstrate. Therefore, according this embodiment, it is possible toachieve a substrate processing with high uniformity on the principalface of the substrate while decreasing production and running costs.

In a preferred embodiment of the invention, the control unit controlsthe substrate holding rotating mechanism to rotate the substrate at afirst rotational speed when forming a liquid film covering the wholearea of the principal area of the substrate with the liquid film formingunit, and then at a second rotational speed that is slower than thefirst rotational speed when a process liquid is dispensed toward theprincipal face of the substrate via the process liquid nozzle afterformation of liquid film covering the whole area of the principal areaof the substrate.

With this configuration, when a process liquid reserved in a processliquid reservoir is supplied in a single burst toward a principal faceof a substrate and reach thereon, because of the rapid rotation of thesubstrate at the first rotational speed, the process liquid will beinstantaneously spread out by centrifugal force throughout the principalface to instantly form a liquid film covering the whole area of theprincipal face, thereby realizing substantially simultaneous starts ofprocessing with process liquids throughout the principal face of thesubstrate. On the other hand, when a process liquid is supplied via theprocess liquid nozzle after the formation of the liquid film, thesubstrate is slowly rotated at a second rotational speed; thereby anewly supplied process liquid supplied onto the liquid film on theprincipal face of the substrate will be spread in an outwardly radialdirection thereon. Because the rotational speed of the substrate is keptslow during the spread, replacing of process liquids occurs in asubstantially uniform manner at a rotational center part and acircumferential part of the principal face of the substrate; therebyresulting in substantially equal respective processing speeds. In otherwords, processing by process liquids can be started at substantially thesame time throughout the principal face of the substrate, and respectiveprocessing speeds can be almost equalized. As a result of this, furtherimprovements on uniformity of substrate processing can be achieved.

In a preferred embodiment of the invention, the process liquid supplymechanism in the substrate processing apparatus may include a processliquid supply source for connecting a process liquid supply source andthe process liquid nozzle. In this case, the process liquid reservoir ispreferably connected with the process liquid supply path.

With this configuration, a process liquid can be guided into the processliquid reservoir via the process liquid supply path. Also, the processliquid reserved in the reservoir can be supplied onto a principal faceof a substrate via the process liquid supply path.

In a preferred embodiment of the invention, the liquid film forming unitmay include a pressurized gas supply mechanism that pushes out a processliquid reserved in the process liquid reservoir by pressurized air. Withthis relatively inexpensive configuration utilizing pressurized gas,process liquid reserved in the reservoir can be discharged in a singleburst onto a principal face of substrate.

The pressurized gas supply mechanism preferably includes a gas pipeconnected with the process liquid reservoir and a pressurized gas valveinterposed on the gas pipe. In this case, it is preferable that theprocess liquid supply unit further includes a process liquid valveinterposed on the process liquid line; and the process liquid reservoiris connected with the process liquid supply line at a place between theprocess liquid supply source and the process liquid valve; and theprocess liquid supply unit further includes a relief pipe connected withthe gas pipe and a relief valve interposed on the relief valve.

With this configuration, a process liquid can be reserved in the processliquid reservoir by activating a pump in a state wherein the processliquid valve, the pressurized gas valve, and the relief valve areclosed, to guide a process liquid from the process liquid source intothe process liquid reservoir. In turn, when the process liquid valve isopened, the relief valve is closed, and the pressurized gas valve isopened, the process liquid reserved in the process liquid reservoir ispushed out into the process liquid supply path because of the pressureapplied to the process liquid supply path to be discharged in a singleburst toward the principal face of the substrate via the process liquidnozzle.

It should be apparent that supplying of a process liquid into theprocess liquid reservoir does not necessarily have to be conducted viathe process liquid supply line and may be conducted via other routeseparately provided. And the discharge of process liquid from theprocess liquid reservoir toward the principal face of the substrate doesnot necessarily have to be conducted via the process liquid supply lineand may also be conducted via a discharge route that is separatelyarranged.

In a preferred embodiment of the invention, the process liquid reservoirincludes a first process liquid reservoir for reserving a first type ofprocess liquid and a second process liquid reservoir for reserving asecond type of process liquid; and the liquid film forming unit isconfigured such that the first type of process liquid and the secondtype of process liquid are discharged in a single burst respectivelyfrom the first and the second process liquid reservoirs and aresupplied, as they are mixed together, onto a principal face of thesubstrate.

With this configuration, the whole area of the principal face of thesubstrate can be instantaneously covered with a prepared process liquidby reserving the first and the second type of process liquidsrespectively in the first and the second process liquid reservoirs,mixing them (for example, mixing them within pipes) and supplying them,shortly after the mixing, onto the principal face of the substrate.

Concerning the above configuration, it might be conceivable to have analternative configuration in which a first and second flow controlvalves are individually disposed at on a first and second process liquidlines so as to, when processing starts, supply the first and secondprocess liquid each in large volumes into a mixing point thereof, forexample. But such configuration has problems not only in that flowcontrol valves are expensive but also in that mix ratios for the firstand the second process liquid tend to become unstable when flow ratesvary. That is, it is difficult to maintain mix ratios for processliquids when flow rates for the process liquids vary. The aforementionedconfiguration according to a preferred embodiment of the inventionprovides a solution to those problems.

In a preferred embodiment of the invention, a liquid film forming unitincludes a transfer mechanism for transferring the process liquidreservoir between a process liquid discharge position above a principalface of a substrate held with a substrate holding rotating mechanism anda retreat position away from the process liquid discharge position; anda process liquid discharge mechanism for discharging a process liquidreserved in the process liquid reservoir at the process liquid dischargeposition.

With this configuration, the process liquid reservoir can be transferredto the process liquid discharge position above the principal face of thesubstrate when necessary so that it can discharge the process liquidtherefrom. Thus, taking advantage of gravity force, the process liquidcan be discharged in a single burst. Adding to this, the process liquidreservoir can be retreated from near the principal face of the substrateso as to avoid mechanical interferences, either when a substrate to beprocessed is transferred into or a processed substrate is transferredout of the substrate holding rotating mechanism. The process liquidreservoir can also be retreated into a retreat position so as to avoidoccurrence of dripping of process liquids etc. from the reservoir ontothe principal face of the substrate.

It is preferable that the process liquid to be discharged from theprocess liquid nozzle is supplied into the process liquid reservoir whenthe process liquid reservoir is positioned at the retreat position.

With this configuration, the process liquid can be supplied using theprocess liquid nozzle when the process liquid reservoir is positioned atthe retreat position. Thus, since it is unnecessary to provide adedicated component for supplying process liquid supply into processliquid reservoir, it is possible to reduce costs.

For example, when a nozzle transfer mechanism for transferring a processliquid nozzle between a process position opposing the principal face ofthe substrate and a nozzle retreat position retreated from the processposition, the nozzle retreat position is preferably positioned at aposition from which the process liquid nozzle is able to discharge aprocess liquid toward a process liquid inlet for the process liquidreservoir positioned at the retreat position. More specifically, thenozzle retreat position may be just above the retreat position for theprocess liquid reservoir. With such a configuration, a process liquidcan be supplied into a process liquid reservoir utilizing a period whenthe process liquid nozzle is not occupied for supplying of processliquids onto the principal face of the substrate.

In a preferred embodiment of the invention, a substrate processapparatus further includes a process liquid recovering mechanism whichrecovers a process liquid supplied from the process liquid nozzle,supplied onto the substrate, and then processed on the substrate heldwith the substrate holding rotating mechanism; and guides the processliquid into the process liquid reservoir.

With this configuration, used process liquids can be recovered, reservedin the process liquid reservoir, and recycled to form a liquid filmcovering the whole area of the principal face of the substrate;therefore contributing to a further decrease in an consumption amount ofprocess liquids and a consequential decrease in running costs.

It is another object of the invention to provide a substrate processmethod which comprises a substrate rotating step for rotating asubstrate; a reserving step for reserving a process liquid sufficient toform a liquid film covering the whole area of the principal face of thesubstrate; liquid film forming step for forming the liquid film coveringthe whole area of the principal area of the substrate; and a dispensingstep after the liquid film forming step for dispensing a process liquidfrom a process liquid nozzle onto the principal face of the substratebeing rotated.

In a preferred embodiment of the invention, the substrate rotating stepincludes a step for rotating the substrate at a first rotational speedin parallel with the liquid film forming step; and a step for rotatingthe substrate at a second rotational speed slower than the firstrotational speed in parallel with the dispense step for dispensing aprocess liquid from the process liquid nozzle after the liquid filmforming step.

The liquid film forming step may include a pressurized gas supplyingstep for pushing out a process liquid reserved in the process liquidreservoir by pressurized gas.

The process liquid reservoir may include a first process liquidreservoir for reserving a first type of process liquid and a secondprocess liquid reservoir for reserving a second type of process liquid.In this case, the liquid film forming step may include a step whereinthe first type of process liquid is discharged in a single burst fromthe first process liquid reservoir, the second type of process liquid isdischarged in a single burst from the second process liquid reservoir,and both of the liquids are supplied, as they are being mixed together,toward the principal face of the substrate.

The liquid film forming step may include a process liquid dischargingstep for discharging a process liquid reserved in the process liquidreservoir at a process liquid discharging position above the principalface of the substrate being rotated.

The reserving step for reserving step for reserving a process liquid inthe process liquid reservoir may include a step wherein the processliquid reservoir is disposed at the retreat position retreated from theposition above the principal face of the substrate; and a process liquidis dispensed from the process liquid nozzle into the process liquidreservoir.

The substrate processing method according to the present invention mayfurther include a process liquid recovery step for recovering theprocess liquid which is supplied onto the substrate from the processliquid nozzle and used for processing and for guiding the process liquidinto the process liquid reservoir.

The aforementioned and other objects, features, and effects of thepresent invention shall be clarified by the following description of apreferred embodiment with references to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a configuration of a substrate processing apparatusin accordance with a first embodiment of the present invention.

FIG. 2 is a flowchart showing steps of the substrate processingapparatus.

FIG. 3 is a schematic graph illustrating etching differences between ata rotational center and an edge portion of a substrate, wherein etchingliquid is used as chemical liquid, and substrate rotational speed isrelatively slow.

FIG. 4 is a schematic graph illustrating etching differences between ata rotational center and an edge portion of substrate, wherein etchingliquid is used as chemical liquid, and substrate rotational speed isrelatively fast.

FIG. 5 illustrates a configuration of a substrate processing apparatusin accordance with a second embodiment of the present invention.

FIG. 6A and FIG. 6B illustrate a configuration of a substrate processingapparatus in accordance with a third embodiment of the presentinvention.

FIG. 7 illustrates a configuration of a substrate processing apparatusin accordance with a fourth embodiment of the present invention.

FIG. 8 illustrates a configuration of a substrate processing apparatusin accordance with a fifth embodiment of the present invention.

FIG. 9 illustrates a configuration of a substrate processing apparatusin accordance with a sixth embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 illustrates a configuration of a substrate processing apparatusconcerning the first preferred embodiment of the invention. Thesubstrate processing apparatus is single wafer type substrate processingapparatus for processing a wafer W such as semiconductor wafers withprocess liquids, one wafer at a time. This substrate process apparatuscomprises a process chamber 1; a spin chuck 2 which is arranged withinthe process chamber 1 and is able to horizontally hold and rotate awafer W around a vertical axis; a rotation drive mechanism 3 whichrotates the spin chuck 2 around the vertical axis; a process liquidsupply unit 4 which supplies a chemical liquid to the substrate W heldwith the spin chuck 2; and a rinse liquid supply unit 8 which supplies arinse liquid (for example, deionized water) toward the substrate W heldwith the spin chuck 2.

The substrate processing apparatus further includes a chemical liquidbuffer tank 5 for temporarily reserving a chemical liquid that is a sametype of chemical liquid supplied by the chemical liquid supply unit 4;and a pressurized gas supply unit 6 for supplying a pressurized gas intothe chemical liquid buffer tank 5 to push out the chemical liquidreserved in the chemical liquid buffer tank 5 in a single burst. Thespin chuck 2 is accommodated inside of a process cup 9. The process cup9 is formed in a tubular shape with an upper opening and a bottom and isconfigured so as to receive processing liquids which are being laterallyflied out as a result of centrifugal force applied thereto. Thesubstrate processing apparatus further includes a rotating drivemechanism 3, a chemical liquid supply unit 4, and a control unit 7 forcontrolling the pressurized gas supply unit 6 or the like.

The spin chuck 2 holds the substrate W in a horizontal posture, with theprincipal face of the substrate to be treated facing upward. Therotation drive mechanism 3 rotates the substrate W around the verticalaxis by rotating the spin chuck 2. In this manner, a substrate holdingrotating mechanism is configured with the spin chuck 2 and the rotationdrive mechanism 3. Rotational speed of the spin chuck 2, or namely therotational speed of the substrate W, is variably controlled by controlunit 7 that controls rotation drive mechanism 3.

The chemical liquid supply unit 4 includes a chemical liquid nozzle 11disposed inside of the process chamber 1; and a chemical liquid pipe 13(an example for process liquid supply line), an end of which isconnected to the chemical liquid nozzle 11 and another end of whichextends to outside of the process chamber 1 to be connected to thechemical liquid tank 12. The chemical liquid tank stores a chemicalliquid which is prepared beforehand to a predetermined density. Thechemical liquid may be of etching liquid (for example, hydrofluoricacid). The chemical liquid supply unit 4 further includes a chemicalliquid valve 14 (an example of process liquid valve) interposed at aposition along the chemical liquid pipe 13; a flowmeter 15 interposed ata position along the chemical liquid pipe 13 at a more upstream sidethan the chemical liquid valve 14; and a pump 16 interposed at aposition along the chemical liquid pipe 13 at a more upstream side thanthe flowmeter 15. The pump 16 and the chemical tank 12 constitute achemical liquid supply source for pushing out chemical liquids into thechemical liquid pipe 13. Output signals of flowmeter 15 are configuredto be inputted into the control unit 7. The control unit 7 controlsopen/close of the chemical liquid valve 14 and operations of the pump16. When the pump 16 is activated with the chemical liquid valve 14opened, a chemical liquid reserved in the chemical liquid tank 12 ispumped out, flows through the chemical liquid pipe 13, and is suppliedinto the chemical liquid nozzle 11. The pump 16 is driven so thatchemical liquid is dispensed from the chemical liquid nozzle 11 at apredetermined flow rate. The flow rate is under surveillance based onoutputs from the flowmeter 15 in that whether it is in a tolerance rangeor not.

The chemical liquid nozzle 11 is arranged so that it can be transferredinside the process chamber by a nozzle transfer mechanism 17. The nozzletransfer mechanism 17 includes swing arm 18 arranged inside the processchamber 1 and a swing drive mechanism 19 that swings the swing arm 18around the vertical axis. The chemical liquid nozzle 11 is fixed on thedistal portion of the swing arm 18. The swing arm 18 extendshorizontally and is swung around the vertical axis set along the spinchuck 2 by the swing drive mechanism 19; thereby the distal portion ofthe swing arm 18 is transferred along an arcuate trajectory in ahorizontal plane. This allows the chemical liquid nozzle 11 to betransferred between a process position (above the spin chuck 2) opposingthe upper face of the substrate W held by the spin chuck 2 and a retreatposition retreated from above the spin chuck 2. The process positionallows the chemical liquid nozzle to dispense chemical liquid toward therotational center of the substrate, for example.

A rinse liquid supply unit 8 includes a rinse liquid nozzle 21 arrangedinside the process chamber 1 and a rinse liquid pipe 23 one end of whichis connected with the rinse liquid nozzle 21 and another end of whichextends to outside of the process chamber 1 to be connected to the rinseliquid source 22. The rinse liquid supply unit 8 further includes arinse liquid valve 24 interposed at a position along the pipe 23. Acontrol unit 7 controls open/close of the rinse valve 24. When the rinsevalve 24 is opened, a rinse liquid from the rinse liquid source 22 flowsthrough the rinse liquid pipe 23 and is supplied into the rinse liquidnozzle 21; thereby allowing the rinse liquid nozzle 21 to dispense therinse liquid to be supplied toward the principal face (upper face) of asubstrate W.

The rinse liquid nozzle 21 may be mounted, along with the chemicalliquid nozzle 11, on the swing arm 18 of the nozzle transfer mechanism17. Also, the rinse liquid nozzle 21 may be transferrable, by a nozzletransfer mechanism alternative to the nozzle transfer mechanism, betweena process position above the spin chuck 2 and a retreat position forretreating from above the spin chuck 2 to sideway. Further, rinse liquidnozzle 21 may take the form of nozzle fixture fixed inside the processchamber 1.

A chemical liquid buffer tank 5 is a chemical liquid reservoir having avolumetric capacity to reserve a sufficient quantity of chemical liquidsto form a liquid film covering over the whole area of the principal face(upper face) of the substrate W held by the spin chuck 2. The chemicalliquid buffer tank 5 is a hermetically closed reservoir; to the lowerface of which a chemical liquid discharge path 27 is connected, and tothe upper face of which gas pipe 31 is introduced. More specifically,the chemical liquid discharge path 27 is connected with a chemicalliquid pipe 13 at between a pump 16 and a chemical liquid valve 14.Interposed at along the chemical liquid discharge path 27 is a chemicalliquid discharge valve 28; open/close of which is controlled by thecontrol unit 7.

The pressurized gas supply unit 6 is configured so as to push out achemical liquid reserved in the chemical liquid buffer tank 5 bypressurized gas. More specifically, the pressurized gas supply unit 6has a gas pipe 31 connected with the chemical liquid buffer tank 5 and apressurized gas valve 32 interposed at a position along the gas pipe 31.The gas pipe is configured so that pressurized gas from the pressurizedgas supply source 33 is supplied into the gas pipe. Preferably, thepressurized gas is of inert gases such as nitrogen gas or the like.Open/close of the pressurized gas valve 32 is controlled by the controlunit 7.

One end of a relief pipe 35 is connected to the gas pipe 31 at aposition between the chemical liquid buffer tank 5 and the pressurizedgas valve 32, while the another end of which is introduced into thechemical liquid tank 12. At a position along the relief valve 35, arelief valve 36 is interposed. Open/close of the relief valve 36 iscontrolled by the control unit 7.

FIG. 2 is a flowchart illustrating operations of the substrate processapparatus.

When an unprocessed substrate W is introduced into a process chamber 1and handed over onto a spin chuck 2 by a substrate transfer robot, acontrol unit 7 rotates the substrate W at a first rotational speed (forexample, about 1,000 rpm) (step S1). That is, the control unit 7 rotatesthe spin chuck 2 at the first rotational speed by controlling therotation drive mechanism 3. Thereafter, a chemical processing starts.

Before the commencement of chemical processing, the control unit 7executes a chemical liquid injection procedure for injecting a chemicalliquid into the chemical liquid buffer tank 5 (step S11). Specifically,the control unit 7 activates a pump 16 in a state wherein both achemical liquid valve 14 and a pressurized gas valve 32 are closed andboth a chemical liquid discharge valve 28 and a relief valve 36 areopened. Then as a result of this, the chemical liquid pumped out fromthe pump 16 flows into the chemical liquid buffer tank 5 via from thechemical liquid pipe 13 to chemical liquid discharge path 27. Gas in thechemical liquid buffer tank 5 is pushed into the chemical liquid tank 12via from the gas pipe 31 to relief pipe 35. By activating the pump 15for a period corresponding to the amount of chemical liquid to bereserved in the chemical liquid buffer tank 5, requisite quantity ofchemical liquid can be reserved in the chemical liquid buffer tank 5.Thereafter, the control unit 7 closes the relief valve 36 whilemaintaining the activation of the pump 16. Furthermore, the control unit7 opens the pressurized gas valve 32 and supplies a pressurized gas intothe chemical liquid buffer tank 5 to add pressure therewithin (stepS12).

The chemical processing includes a whole-surface-liquid-film formingstep (step S2) and a small-flow-rate process step (step S3).

In the whole-surface-liquid-film forming step (step S2), the whole ofthe chemical liquid reserved in the chemical liquid buffer tank 5 issupplied onto the principal face (upper face) of the substrate W in asingle burst. More specifically, the opening of chemical liquid valve 14by the control unit 7 causes the whole quantity of the chemical liquidreserved in the chemical liquid buffer tank 5 to be pushed out into thechemical liquid pipe 13 by pressurized gas, to be discharged in a singleburst in large quantity from the chemical liquid nozzle 11 toward theupper face of a substrate W (step S13). Before the discharge, thecontrol unit 7 transfers the chemical liquid nozzle 11 to a processingposition above of the spin chuck 2. Since the chemical liquid isdispensed in large quantity from the chemical liquid nozzle 11 and thesubstrate W is rotated at a first rotational speed, the chemical liquidinstantaneously spreads out throughout the whole area of the principalface of the substrate W to form a liquid film covering the whole area ofthe principal face of the substrate W. To be more specific, dispensingof chemical liquid reserved in the chemical liquid buffer tank 5 for anamount of 30 to 70 cc is completed within about 2 seconds for example;thereby instantaneously covering the whole area of the principal face ofthe substrate W with a liquid film.

Thereafter the control unit 7 closes the pressurized gas valve 32 tostop adding pressure, and closes the chemical liquid discharge valve 28(step S14). With this, a chemical liquid pumped out from the chemicalliquid tank 12 by the pump 16 is supplied via from the chemical liquidpipe 13 to the chemical liquid nozzle 11, and is dispensed from thechemical nozzle 11 at a small-flow-rate to be supplied onto theprincipal face of the substrate W. In this manner, the small-flow-rateprocess (step S3) is performed. In step S3, the control unit 7 decreasesthe rotational speed of the spin chuck 2 (thus that of the substrate W)to a second rotational speed (for example, about 100 rpm) that is slowerthan the first rotational speed, by controlling a rotation drivemechanism 3. So, in the small-flow-rate process step (step S3), achemical liquid is supplied to the liquid film on the surface of thesubstrate W rotated at a slow speed. The flow rate for the chemicalliquid from the chemical liquid nozzle 11 in the step S3 may be about0.25 liter/minute, for example. Such a small-flow-rate process continuedfor about 30 seconds.

Thereafter the control unit 7 closes a chemical liquid valve 14,deactivates the pump 16 to terminate the chemical processing, and thenexecutes a rinsing step (step S4). Specifically, the control unit 7opens the rinsing liquid valve 24 to allow the rinsing liquid nozzle 21to dispense a rinsing liquid toward the principal face of the substrateW. Furthermore, the control unit 7 controls the rotation drive mechanism3 to control a rotational speed of the spin chuck 2 (consequently, thatof the substrate W as well) at a predetermined rinse process speed (forexample, 1,000 rpm). With this, the rinsing liquid supplied to theprincipal face of the substrate W spreads over the whole area of thesubstrate to be substituted with the chemical liquid. The supplying ofthe rinsing liquid continues for about 30 seconds, for example.

Thereafter the control unit 7 stops dispensing of the rinsing liquid byclosing the rinsing liquid nozzle 21 and the rinsing process (step S4)ends. Then, the control unit 7 executes a drying step (step S5) bycontrolling the rotation drive mechanism 3 to control a rotational speedof the spin chuck 2 (that of the substrate W as well) at a predetermineddrying process speed (for example, about 3,000 rpm). With this, residueof water on the principal face of the substrate W is thrown off withcentrifugal forces applied thereon. This spin dry processing continuesabout 10 seconds, for example.

Followed by completion of the drying step in the manner described above,the processed substrate W is transferred to the outside of the processchamber 1 by a substrate transfer robot. Thereafter, each time anunprocessed substrate W is transferred into the process chamber 1,similar procedures will be repeated.

FIG. 3 is a schematic graph illustrating differences between a case of arotational center portion and a case of a peripheral (edge) portion of asubstrate. Horizontal axis indicates starting time of etching liquiddispensing, and longitudinal axis indicates amount of etching.

In a case that a etching liquid is dispensed at the center of asubstrate, it takes some time before the etching liquid reaches to theperipheral portion of the substrate with centrifugal forces appliedthereto. Thus, there will be a time delay D for a starting time of theetching at peripheral portion of the substrate, compared to that at therotational center of the substrate. As time lapses for an amount of thedelay D, etching at the rotational center of the substrate advances toyield an amount of ΔE of etching. Such etching difference inevitablyoccurs no matter how long the overall etching-liquid-dispense-time mightbe.

Thus, the aforementioned embodiment is configured such that, uponstarting of a chemical liquid processing, a chemical liquid reserved inthe chemical liquid buffer tank 5 is dispensed in a single burst ontothe principal face of the substrate W, instantaneously covering thewhole area thereof with a liquid film of the chemical liquid. Therebythe delay D can be decreased to substantial zero with thisconfiguration; therefore it is possible to eliminate the etching amountdifference resulted from the time difference between the rotationalcenter and the peripheral portion of the substrate W.

Furthermore, the inventors of the present invention have found out thatwhen flow rate of the etching liquid is suppressed (for example, 0.25liter/minute) to decrease amount of consumption thereof, there exists arelationship between uniformities of etching over a face of a substrateand rotational speeds for the substrate. To be more specific, whenrotational speed of substrate is high (for example, at 1,000 rpm), linesin FIG. 4 representing etching amount at the center and at a peripheralportion of the substrate are not in parallel to each other. This meansthat etching rate is higher at the rotational center than at aperipheral portion of the substrate; consequently, longer dispensingtime of etching liquid yields greater difference of respective etchingamounts.

Thus, according to aforementioned embodiment, in the small-flow-rateprocessing step, a rotational speed of the substrate is set to a secondrotational speed that is slow. With this setting, chemical liquidprocessing at the rotational center and at a peripheral portion of thesubstrate proceeds almost concurrently. As a result of this, uniformprocessing by chemical liquids over the whole area of the principal faceof the substrate W can be realized.

As described above, according to this embodiment, a liquid film coveringthe whole of area of a principal face of a substrate W can be formedwithout using expensive parts such as flow control valves by employing aconfiguration such that a chemical liquid reserved in the chemicalliquid buffer tank 5 is supplied onto the substrate in a single burst.After that, since only a small-flow-rate of chemical liquid is requiredfor supplying from the chemical nozzle 11, running costs can bedecreased by suppressing amounts of consumption for chemical liquidswithout damaging process uniformity within the principal face of thesubstrate W. In this manner, a substrate processing with high uniformitywithin a substrate face can be realized while decreasing bothmanufacturing and running costs.

Furthermore, according to this embodiment, when a chemical liquidreserved in the chemical liquid buffer tank 5 is supplied onto theprincipal face of the substrate W in a single burst, a liquid filmcovering over the whole area of the principal face of the substrate Wcan be instantaneously formed due to a rapid rotation of the substrate Wat a first rotational speed. Thereby, chemical processing all over theprincipal face of the substrate W can be started substantiallysimultaneously. On the other hand, when a chemical liquid is dispensedfrom the chemical liquid nozzle 11 after formation of a chemical film,rotational speed of the substrate is set to a second rotational speedwhich is slower. The rotation spreads a new chemical liquid, suppliedonto the liquid film on the principal face of the substrate W, in anoutwardly radial direction. By maintaining the slow rotational speedwhile the new added chemical spreads, chemical liquids replacements atin the vicinity of the rotational center and peripheral portion advancenearly equally, thus resulting in nearly equal processing rates. Inother words, it is possible to start processing with chemical liquidthroughout the principal face of the substrate W at a substantiallysimultaneous time, and it is also possible to achieve nearly homogeneousprocessing rates, thereby improving substrate processing over the faceof the substrate.

FIG. 5 illustrates a configuration of a substrate processing apparatusaccording to the second embodiment of the invention. In FIG. 5, partsalready shown in aforementioned FIG. 1, are shown correspondingreference numerals.

In this embodiment, a chemical liquid buffer tank 5 is provided insideof a process chamber 1. And a buffer tank transfer mechanism 40 isprovided for transferring the chemical liquid buffer tank 5 between adischarge position which is above a spin chuck 2 and a retreat positionwhich is at a sideway from above the spin chuck 2. The buffer mechanism40 may include a horizontal swing arm supporting the chemical liquidbuffer tank 5 at a distal portion thereof, a swing drive mechanism forswinging the swing arm around a vertical axis provided outside of aprocessing cup 9, and an up/down drive mechanism for movingupwardly/downwardly the swing arm, for example. In this case, theretreat position may be arranged at a sideway of processing cup 9, forexample

A chemical liquid discharge path 27 is downwardly communicated, and achemical liquid discharge valve 28 is interposed at a positiontherealong. An end of the chemical liquid injection pipe 41 is connectedwith the chemical liquid buffer tank 5. Another end of the chemicalliquid injection pipe 41 is connected with, at between a chemical liquidvalve 14 and a pump 6, a chemical liquid pipe 13. A chemical liquidinjection valve 42 is interposed at a position along the chemical liquidinjection pipe 41. Movements of buffer tank transfer mechanism 40 andopen/close of chemical liquid injection valve 42 are controlled by acontrol unit 7.

Other parts of the configuration should be arranged in the same manneras described in the first embodiment.

Injection of chemical liquids into the chemical liquid buffer tank 5proceeds as follows. A control unit 7 closes a chemical valve 14, apressurized gas valve 32 and a chemical liquid discharge valve 28 andactivates a pump 16, with a relief valve 36 and a chemical liquidinjection valve 42 being opened. Thereby a chemical liquid pumped outfrom the pump 16 flows into the chemical buffer tank 5, via from achemical liquid pipe 13 through a chemical liquid injection pipe 41. Gasin the chemical liquid buffer tank 5 is pushed out into a chemicalliquid tank 12 via from a gas pipe 31 through a relief pipe 35. Byactivating the pump 16 for a period of time corresponding to the amountof chemical liquid to be reserved in the chemical liquid buffer tank 5,required amount of chemical liquid can be reserved in the chemicalliquid buffer tank 5. After that, the control unit 7 closes the reliefvalve 36 and the chemical liquid injection valve 42, while maintainingthe activation of the pump 16. Furthermore, the control unit 7 opens thepressurized gas valve 32, supplies pressurized gas into the chemicalliquid buffer tank 5, and adds pressure inside the chemical liquidbuffer tank 5.

Process flow proceeds in the same manner as heretofore described in thefirst embodiment (see FIG. 2). That is, chemical processing in thisembodiment includes a whole-surface-liquid-film forming step (see step 2in FIG. 2) and a small-flow-rate processing step (step 3).

In the whole-surface-liquid-film forming step (step S2), the wholechemical liquid reserved in the chemical liquid buffer tank 5 issupplied toward the principal face (upper face) of the substrate W in asingle burst. To be more specific, a control unit 7 opens a chemicalliquid discharge valve 28. Thereby, the entire amount of chemical liquidreserved in the chemical buffer tank 5 is pushed out by gravity andpressurized gas, to be discharged in a single burst in a large flow ratevia a chemical liquid discharge path 27 toward the upper surface of thesubstrate. So, with this embodiment, a liquid film forming unit isconfigured such that a pressurized gas supply unit 6, a chemical liquiddischarge path 27 and a chemical liquid discharge valve 28 dischargechemical liquids reserved in a chemical liquid buffer tank 5 in a singleburst toward the principal face of a substrate W to cover the whole areaof the principal face. In addition, the control unit 7 controls a buffertank transfer mechanism 40 to transfer the chemical liquid buffer tank 5up to a discharge position above the chemical liquid buffer tank 5,prior to opening of the chemical liquid discharge valve 28.

The discharge of the chemical liquid from the chemical liquid buffertank 5 in a single burst at a large flow rate as well as the rapidrotation of the substrate W at a first rotational speed, causes aninstantaneous spread of chemical liquid within the whole area of thesubstrate face, to form a liquid film covering the whole area of theprincipal face of the substrate W. To be more specific, dispensing ofchemical liquid reserved in the chemical liquid buffer tank 5 for anamount of 30 to 70 cc is completed within about 2 seconds for example;thereby instantaneously covering the whole area of the principal face ofthe substrate W with a liquid film.

After this, the control unit 7 stops adding pressure by closing apressurized gas valve 32, and then closes the chemical liquid dischargevalve 28. Furthermore, the control unit 7 transfers the chemical liquidbuffer tank 5, by controlling the buffer tank transfer mechanism 40, toa retreat position for retreating from above of the spin chuck 2. Then,the control unit 7 opens a chemical liquid valve 14 and chemical liquidis dispensed in a small-flow-rate, from a chemical liquid nozzle 11toward the principal face of the substrate W. In this manner,small-flow-rate processing step (step S2) is performed. Before the abovedispensing, the control unit 7 transfers the chemical liquid nozzle 11to a processing position above the spin chuck 2 by controlling a nozzletransfer mechanism 17.

The processes thereafter are performed as described in the same manneras described in the first embodiment.

As in described hereinabove, according to this embodiment, a chemicalliquid buffer tank 5 can be transferred, when required, to a dischargeposition that is above the principal face of a substrate W to dischargea chemical liquid therefrom. Releasing of the chemical liquid may beconducted in a single burst by taking advantages of gravitationalforces. The chemical liquid buffer tank 5 can be retreated from aposition above of the principal face of a substrate W, when thesubstrate W to be processed is transferred to a spin chuck 2 or when theprocessed substrate W is transferred from the spin chuck 2, so that itmay not interfere with parts of the apparatus. The chemical liquidbuffer tank 5 can also be retreated to a retreat position, either when achemical liquid nozzle 11 is dispensing chemical liquid or when a rinseliquid nozzle 21 is dispensing rinse liquid, so as to avoid drippings ofchemical liquids or the like therefrom onto the principal face of thesubstrate W.

The embodiment described above can have other effects and advantages ina similar manner as described in the first embodiment.

FIG. 6A and FIG. 6B illustrate a configuration of a substrate processingapparatus according to the third embodiment of the invention. In FIG. 6Aand FIG. 6B, like parts shown in aforementioned FIG. 5 are givencorresponding like reference numerals. FIG. 6B is a plan view of aconfiguration inside of the process chamber 1 shown in FIG. 6A.

Compared to the second embodiment, neither components concerning apressurized gas supply nor components related to a chemical liquidinjection pipe 41 are included in this embodiment.

A retreat position for a chemical liquid buffer tank 5 which is to betransferred by a buffer tank transfer mechanism 40, is positioned justbelow a nozzle retreat position for a chemical liquid nozzle 11. In FIG.6A, a discharge position for the chemical liquid buffer tank 5 isrepresented by alternate long and two short dashes lines, and a retreatposition is represented by solid lines. A control unit 7 opens achemical liquid valve 14 when a chemical liquid buffer tank 5 is at aretreat position and a chemical liquid nozzle 11 is at a nozzle retreatposition. Thereby, a chemical liquid brought into a chemical liquid pipe13 by pump 16, is dispensed from a chemical liquid nozzle 11. Then thechemical liquid is injected, from a chemical liquid inlet 45 formed onthe upper face of the chemical liquid buffer tank 5, into the inside ofthe chemical liquid buffer tank 5. In this way, it is possible toperform chemical liquid injection into the chemical liquid buffer tank5.

In whole area of liquid film forming step (step 2 in FIG. 2), the wholechemical liquid reserved in a chemical liquid buffer tank 5 is suppliedin a single burst onto the principal face (upper face) of a substrate W.To be more specific, a controller 7 opens a chemical liquid dischargevalve 28. As a result of this, the entire amount of chemical liquidreserved in the chemical liquid tank 5 flows down in a single burst in alarge flow rate by gravity, through a chemical liquid discharge path 27toward the upper face of a substrate W. As described above, with thisembodiment, a chemical liquid discharge path 27 and a chemical liquiddischarge valve 28 constitute a liquid film forming unit forinstantaneously forming a liquid film covering the whole area of theprincipal face of a substrate W. As may be apparent from the foregoingembodiments, the control unit 7 transfers the chemical liquid buffertank 5 at a discharge position (a position indicated by alternate longand two short dashes lines in FIG. 6A) above a spin chuck 2 bycontrolling a buffer tank transfer mechanism 40, before opening of thechemical liquid discharge valve 28. Releasing of chemical liquid fromthe chemical liquid buffer tank 5 in a large flow rate while thesubstrate W being rapidly rotated at a first rotational speed, resultsin an instantaneous spread of the chemical liquid over the whole areawhich results in a formation of a liquid film covering the whole area ofthe principal face of the substrate W.

Processes thereafter are performed in a similar manner as in the secondembodiment.

According to this embodiment, when a chemical liquid buffer tank 5 ispositioned at a retreat position, chemical liquid can be injected into achemical liquid buffer tank 5 by utilizing a chemical liquid nozzle 11.Thereby, it is possible to reduce costs with this embodiment owning tothe fact that there is no need for dedicated components for chemicalliquid injection.

FIG. 7 illustrates a configuration of a substrate processing apparatusaccording to the fourth embodiment of the invention. In FIG. 7, likereference numerals represent corresponding like parts shown in theaforementioned FIG. 1.

With this embodiment, used chemical liquid supplied to a substrate Wheld by a spin chuck 2 is received by a process cup 9, is flowed througha chemical liquid recovering pipe 48 (an example for a processing liquidrecovering unit), and is recovered to be guided into a chemical liquidbuffer tank 5. At a position along the chemical liquid recovering pipe48, a three-way valve 49 is interposed. The three-way valve 49 isconnected with a drain pipe 50. The three-way valve 49 is controlled bya control unit 7.

When both upstream side (treatment cup 9 side) and downstream side(chemical liquid buffer tank 5 side) of the chemical liquid recoverypipe 48 are communicated by controlling the three-way valve 49, usedchemical liquid flows through a chemical liquid recovering pipe 48 andthen is injected into a chemical liquid buffer tank 5. Thereby it ispossible to conduct injections of chemical liquid into the chemicalliquid buffer tank 5. When both upstream side and a drain pipe 50 arecommunicated by controlling the three-way valve, used chemical liquid isguided from the chemical liquid recovery pipe into the drain pipe 50,only to be drained out. Thereby, it is possible to avoid injection ofexcessive chemical liquid into the chemical liquid buffer tank 5. Inthis state, it is also possible to inject a chemical liquid form achemical liquid pipe 13 into the chemical liquid buffer tank 5.

According to this embodiment, it is possible to recover used chemicalliquid and have it reserved in the chemical buffer tank 5 to reuse it toform a liquid film covering the whole area of the principal face of asubstrate W, as described above. Thus it is possible to further decreaseamount of consumption for chemical liquid, thereby further reducingrunning costs.

FIG. 8 illustrates a configuration of a substrate processing apparatusaccording to the fifth embodiment of the invention. In FIG. 8, likereference numerals represents corresponding like parts shown in theFIG. 1. With this embodiment, adding to the components shown in FIG. 1,a rinse liquid buffer tank 55 and a pressurized gas supply unit 60 forpushing out rinse liquid reserved in the rinse liquid buffer tank 55,are provided.

The rinse liquid buffer tank 55 is a reservoir for rinse liquid, capableof reserving rinse liquid sufficient to form a liquid film covering thewhole area of the principal face (upper face) of a substrate W held by aspin chuck 2. The rinse liquid buffer tank 55 is a closed vessel; arinse liquid discharge path 57 being connected with the lower facethereof and a gas pipe 61 being introduced from the upper face thereof.The rinse liquid discharge path 57 is connected with a rinse liquid pipe23. To be more specific, the rinse liquid discharge path 5 is connectedat a point between a rinse liquid source 22 and a rinse liquid valve 24,with the rinse liquid pipe 23. A rinse liquid discharge valve 58 isinterposed at a position along the rinse liquid discharge path 57.Open/close of the rinse liquid discharge valve 58 is controlled by acontrol unit 7.

In order to push out rinse liquid reserved in the rinse liquid buffertank 5, a pressurized gas supply unit 60 is provided. The pressurizedgas supply unit 60 has a gas pipe 61 connected with a rinse liquidbuffer tank 55, and pressurized gas valve 62 interposed at a positionalong the gas pipe 61. The gas pipe 61 is arranged so as to be supplieda pressurized gas from a pressurized gas source 63. It is preferablethat the pressurized gas is an inert gas such as nitrogen gas and thelike. Open/close of the pressurized gas valve 62 is controlled by thecontrol unit 7.

One end of the relief pipe 65 is connected with the gas pipe 61 at apoint between the rinse liquid buffer tank 55 and the pressurized gasvalve 62. The other end of the relief pipe 35 is communicated with openatmosphere. The relief valve 66 is interposed at a position along therelief pipe 65. Open/close of the relief valve 66 is controlled by thecontrol unit 7.

Injection of rinse liquid into the rinse liquid buffer tank 55 isperformed as follows. That is, the control unit 7 closes both of therinse liquid valve 24 the pressurized gas valve 62, and then opens bothof a rinse liquid discharge valve 58 and a relief valve 66. Thereby,being pushed by pressure from the rinse liquid source 22, the rinseliquid flows, via from the rinse liquid pipe 23 to the rinse liquiddischarge path 57, into the rinse liquid buffer tank 55. Gas in therinse liquid buffer tank 55 is pushed out, via from the gas pipe 61 tothe relief pipe 65, into the open atmosphere. Under this condition, bywaiting for a lapse of time corresponding to the amount of the rinseliquid to be reserved in the rinse liquid buffer tank 55, requisiteamount of rinse liquid can be reserved in the rinse liquid buffer tank55. Thereafter, the control unit 7 closes the relief valve 66.Furthermore, the control unit 7 opens the pressurized gas valve 62 tosupply pressurized gas into the rinse liquid buffer tank 55 and to addpressure therein. Processes as such are performed until a rinse step(step S4 in FIG. 2) starts (for example, at during chemical liquidprocessing).

After this, when the control unit 7 opens the rinse liquid valve 24 tostart a rinse step, the entire amount of rinse liquid reserved in therinse liquid buffer tank 55 is supplied in a single burst onto theprincipal face (upper face) of a substrate W. To be more specific, theentire amount of the rinse liquid, reserved in the rinse liquid buffertank 55, is pushed out to the rinse liquid pipe 23 by pressurized gas,and is dispensed from the rinse liquid nozzle 21 in a single burst in alarge flow rate toward the upper face of the substrate W. Because of thefact that rinse liquid is dispensed from the rinse liquid nozzle 21 at alarge flow rate and the substrate W is rapidly rotated in rinse processspeed, the rinse liquid instantaneously spreads over the whole area ofthe principal face of the substrate W to form a liquid film covering thewhole area of the principal face of the substrate W. More specifically,for example, 30 to 70 cc of chemical liquid reserved in the chemicalliquid buffer tank 5 would be dispensed completely within on the orderof 2 seconds. Thereby the whole area of the principal face of thesubstrate W is instantaneously covered with a liquid film; thus enablingsubstantially simultaneous termination of the process with chemicalliquid over the whole area of the principal face of the substrate W.

Thereafter the control unit 7 closes the pressurized gas valve 62 tostop adding pressure, and closes the rinse liquid discharge valve 58.After that, a rinse liquid from the rinse liquid source 22 is dispensedtoward the principal face of the substrate W at a normal flow rate.

As described herewith, owning to the fact that it is possible to supplya large amount of rinse liquid in a single burst onto the principal faceof the substrate W at the beginning of a rinsing step according to thisembodiment, it is possible to simultaneously stop processing withchemical liquid throughout the whole area of the principal face of thesubstrate W; thereby further improving uniformity of substrateprocessing within the face of the substrate.

FIG. 9 illustrates a configuration of substrate processing apparatusaccording to the sixth embodiment of the invention. In FIG. 9, likereference numerals represents corresponding like parts shown in theaforementioned FIG. 1.

In the aforementioned first to fifth embodiments, examples are shown inwhich already mixed chemical liquid is reserved in a chemical liquidtank 12 only to be dispensed as it is from a chemical liquid nozzle 11.On the other hand, in the sixth embodiment, undiluted solution (chemicalliquid before mixing) is reserved in a chemical liquid tank 12, in whichthe undiluted solution is diluted with a diluting liquid (deionizedwater (DIW) in this embodiment) while flowing through pipes, in order toprepare a chemical liquid mixed to an adequate density.

To be more specific, an undiluted chemical liquid solution valve 74 isinterposed on a chemical liquid pipe 13 at a position between a chemicalliquid valve 14 and a pump 16 (to be more accurate, at between achemical liquid valve 14 and a flowmeter 15). The chemical liquid pipe13 positioned at an upstream side of the undiluted chemical liquidsolution valve 74, is a chemical liquid line through which undilutedchemical liquid solution communicates. A chemical liquid discharge path27 of a chemical liquid buffer tank 5 is connected with the undilutedchemical liquid solution line.

The chemical liquid pipe 13, which is positioned at a point between thechemical liquid valve 14 and the undiluted chemical liquid solutionvalve 74, is arranged such that the undiluted liquid from a dilutionliquid supply unit 81 is supplied thereinto. That is, one end of thedilution liquid pipe 83 is connected with the chemical liquid pipe 13which is positioned between the chemical liquid valve 14 and theundiluted chemical liquid solution valve 74. Another end of the dilutingliquid pipe 83 is connected with a diluting liquid source 82. A dilutingliquid valve 84 and a flowmeter 85 are interposed at a position alongthe diluting liquid pipe 83. Thus, it is possible to mix chemical liquidand diluting liquid at a mixing point 80 of the chemical liquid pipe 13and the diluting liquid pipe 83, at a mix ratio corresponding to a flowrate ratio therebetween, by opening the diluting liquid valve 84,thereby preparing chemical liquid which is diluted to a predetermineddensity. Accordingly, chemical liquid is prepared by diluting anundiluted chemical liquid solution to a predetermined density. Outputsignals of the flowmeter 85 are arranged to be input to the control unit7. Open/close of the diluting liquid valve 84 is arranged to becontrolled by control unit 7.

A substrate processing apparatus according to this embodiment isprovided with a dilution liquid buffer tank 75 (an example of areservoir for process liquid) and a pressurized gas supply unit 90 forpushing out dilution liquid reserved in the dilution liquid buffer tank75. With this embodiment, in whole face liquid film forming step (stepS2 in FIG. 2), both an undiluted chemical liquid solution in a chemicalliquid buffer tank 5 and a dilution liquid in a dilution liquid buffertank 75 are discharged in a single burst as they are mixed together toprepare a chemical liquid; thereby the prepared chemical liquid issupplied in a single burst onto the principal face of a substrate toform a liquid film which covers the whole area of the principal face ofthe substrate held by a spin chuck 2. Accordingly, the chemical buffertank 5 and the dilution liquid bugger tank 75 serve as reservoirs forprocessing liquids, having a volume capacity to be able to reservepredetermined amount of undiluted chemical liquid and dilution liquid,respectively, in such a way that the amount of chemical liquid preparedby mixing them together is sufficient to form a liquid film covering thewhole area of the principal face (upper face) of a substrate W held bythe spin chuck 2.

The dilution liquid buffer tank 75 is a closed vessel, a diluting liquiddischarge path 77 is connected with the lower face thereof, and a gaspipe 91 is introduced from the upper face thereof. The dilution liquiddischarge path 77 is connected with a dilution liquid pipe 83. To bemore specific, the dilution liquid discharge path 77 is connected with adilution liquid pipe 83, at a position between the dilution liquid valve84 and the dilution liquid source 83 (more precisely, at between thedilution liquid valve 84 and the flowmeter 85). A dilution liquiddischarge valve 78 is interposed at a position along the dilution liquiddischarge path. Open/close of the dilution liquid discharge valve 78 iscontrolled by the control unit 7.

A pressurized gas supply unit 90 is so configured as to push outdilution liquid reserved in the dilution liquid buffer tank 75 bypressurized gas. That is, the pressurized gas supply unit 90 is providedwith a gas pipe 91 connected with the dilution liquid buffer tank 75,and a pressurized gas valve 92 interposed at a position along the gaspipe 91. The gas pipe 91 joins a gas pipe 31 at a upstream side of apressurized gas valve 32, and is so arranged as to be supplied withpressurized gas from a pressurized gas source 33. Open/close of apressurized gas valve 92 is controlled by the control unit 7.

One end of a relief pipe 95 is connected with the gas pipe 91, at apoint between the dilution liquid buffer tank 75 and the pressurized gasvalve 92. Another end of the relief pipe 95 is open to the atmosphere.Interposed at a position along the relief pipe 95, is a relief valve 96;the control unit 7 controls open/close thereof.

Injection of dilution liquid into the dilution liquid buffer tank 75 isperformed in a manner as follows. That is, the control unit 7 closes thedilution liquid valve 84 and the pressurized gas valve 92, and opens thedilution valve 78 and the relief valve 96; thereby, pushed by initialpressure in the dilution liquid supply source 82, dilution liquid flowsinto the dilution liquid buffer tank 75, via from dilution liquid pipe83 to dilution liquid discharge path 77. The gas in the dilution liquidbuffer tank 75 is pushed out, via from the gas pipe 91 to the reliefpipe 95, into the atmosphere. Under the state described abode, bywaiting for a period of time corresponding to the amount of dilutionliquid to be reserved in the dilution liquid buffer tank 75, a requisiteamount of dilution liquid can be reserved therein. After that, thecontrol unit 7 closes the relief valve 96. Furthermore, the control unit7 opens the pressurized gas valve 92, to allow the dilution liquidbuffer tank 75 to be supplied with pressurized gas, adding pressurewithin the dilution liquid buffer tank 75. Such Operations are performedbefore the chemical liquid processing starts. Similar operations areexecuted for the chemical liquid buffer tank 5, to inject undilutedliquid therein, and to add pressure therein. Other details of operationsare similar to that described in the first embodiment.

The chemical liquid processing includes the whole face liquid filmforming step (step S2 in FIG. 2), and a small-flow-rate processing step(step S3 in FIG. 2) as in the case of the first embodiment.

In the whole-surface-liquid-film forming step (step S2), the entirety ofthe undiluted chemical liquid solution reserved in the chemical liquidbuffer tank 5 and the entire dilution liquid reserved in the dilutionliquid buffer tank 75 are, as a chemical liquid that is mixed andprepared at a mixing point 80, supplied in a single burst onto theprincipal face (upper face) of the substrate W. Specifically, thecontrol unit 7 opens the chemical liquid valve 14, the undilutedchemical liquid solution valve 74 and dilution liquid valve 84. Thereby,the entire amount of the undiluted solution reserved in the chemicalliquid buffer tank 5 is pushed out by pressurized gas to the chemicalliquid pipe 13; and also the entire amount of the dilution liquidreserved in the dilution liquid buffer tank 75 is pushed out bypressurized gas to the dilution liquid pipe 83. Thereby, the undilutedchemical liquid solution and the dilution liquid are mixed together atthe mixing point 80 along the chemical liquid pipe 13 to prepare aprepared chemical liquid which is then dispensed from a chemical liquidnozzle 11 toward the upper face of the substrate W, in a single burstand in a large flow rate. In addition, until before the above dispensingtakes place, the control 7 transfers the chemical liquid nozzle 11 to aprocess position above the spin chuck 2 by controlling a nozzle transfermechanism 17. Because chemical liquid is dispensed from the chemicalliquid nozzle 11 at a large flow rate and the substrate W is rapidlyrotated at a first rotational speed, the chemical liquid instantaneouslyspreads over the whole area of the principal face of the substrate W toform a liquid film covering the whole area of the principal face of thesubstrate W.

Thereafter, the control unit 7 closes the pressurized gas valve 32 and92 in to stop adding pressure, and closes both a chemical liquiddischarge valve 28 and a dilution liquid discharge valve 78. Thereby anundiluted chemical liquid solution pumped out from a chemical liquidtank 12 by a pump 16 and a dilution liquid from a dilution source 82 aresupplied to the mixing point 80, to be mixed at a mix ratiocorresponding to a flow rate ratio thereof, thereby preparing a chemicalliquid. More specifically, flow rate of the undiluted chemical liquidsolution may be on the order of 4 cc/minutes, and flow rate of thedilution liquid may be on the order of 200 cc/minutes. The flow rate(consequently, the mixing ratio) in this case is represented by:

(undiluted chemical liquid solution:dilution liquid)=1:50

The chemical liquid thus prepared is supplied from the chemical liquidpipe 13 to the chemical liquid nozzle 11, and dispensed at asmall-flow-rate from the chemical liquid nozzle 11 to the principal faceof the substrate W. The small-flow-rate processing step is performed inthis manner. In performing the step, the control unit 7 deceleratesrotational speed of the spin chuck 2 or that of the substrate W, to asecond rotational speed by controlling a rotation drive mechanism 3.Accordingly, in the small-flow-rate processing step, chemical liquid issupplied onto liquid film on the surface of the substrate W, at asmall-flow-rate in a state wherein the substrate W is slowly rotated.

Thereafter, the control unit 7 closes the chemical liquid valve 14,undiluted chemical liquid solution valve 74 and dilution liquid valve84, stops the pump 16 to stop the chemical processing, and performsrinsing step. Operations hereafter are performed in the similar manneras in the first embodiment.

As described above, according to this embodiment, it is possible toperform the whole area of liquid film forming process at the beginningof chemical processing in a configuration wherein undiluted chemicalliquid solution and dilution liquid are mixed along pipes to preparechemical liquid. Furthermore, the chemical liquid buffer tank 5 and thedilution liquid buffer tank 5 are provided, respectively correspondingto the undiluted chemical liquid solution and the dilution liquid, so asto allow an undiluted chemical liquid solution and a dilution liquid toflow simultaneously into the chemical liquid pipe 13 to be mixedtogether; because of this, in the entire area liquid forming step aswell, the undiluted chemical liquid solution and a diluting liquid canbe mixed at a predefined mix ratio without experiencing fluctuationsthereof.

As an alternative to the configuration above, it might be conceivable tohave a configuration wherein a first flow rate control valve is arrangedat a position along a undiluted chemical liquid solution line, and asecond flow rate control valve is arranged at a position along adilution liquid pipe so as to respectively supply a undiluted chemicalliquid solution and a dilution liquid, for example. But, configurationsas such present not only a problem as to costs owning to employment ofexpensive flow control valves, but also a problem in that mix ratiobetween undiluted chemical liquid solution and dilution liquid becomesunstable when flow rate changes. In other words, it is difficult tomaintain density of chemical liquid at predetermined level when flowrates of chemical liquid change.

No such problems as such does occur in a configuration according to thisembodiment. Further it is possible to supply a chemical liquid mixed ata certain density onto the principal face of a substrate W in the entirearea liquid film forming step and the small-flow-rate processing step,in spite of the fact that the configuration does not employ expensiveflow control valves; thereby realizing a high-quality substrateprocessing.

Although the preferred embodiments of the present invention have beendescribed hereinabove, it should be clear for those skilled in the artthat the present invention may be put into practice in other modes aswell. For example, the process liquid recovery unit indicated in theconfiguration shown in FIG. 7 may be employed to the configuration shownin FIG. 6B so that used chemical liquid is injected into the chemicalliquid buffer tank 5 at a retreat position. Also, the rinse liquidbuffer tank 55 shown in the FIG. 8 and components related thereto can beprovided in other embodiments. Further, although a configuration whereinthe undiluted chemical liquid solution is diluted by the dilution liquidwas shown in the FIG. 9, the same configuration can be employed moregenerally in such cases that two types of process liquids are mixed inpipe to prepare a prepared process liquid. It should be clear that,mixing of three types of process liquids in pipe can be conducted in asimilar manner. Moreover, while etching liquid is exemplified as a typeof chemical liquid in the aforementioned embodiments, other substrateprocessing adopting other types of chemical liquid such as polymerremoval liquid, resist stripping liquid, silylation liquid, ordeveloping solution or the like are applicable to the present inventionas well. Moreover, application of various change in design are possiblewithin the scope of the invention described in the attached claims.

Although the preferred embodiment of the present invention has beendescribed in detail, the embodiment is merely a specific example used toclarify the technical contents of the present invention, and the presentinvention should not be understood as being limited to this specificexample; and the scope of the present invention is limited solely by theappended claims.

The present application corresponds to Japanese Patent Application No.2011-213272 filed in the Japan Patent Office on Sep. 28, 2011, theentire disclosure of which is incorporated herein by reference.

What is claimed is:
 1. A substrate processing method comprising thesteps of: rotating a substrate; reserving a process liquid in a processliquid reservoir in a predetermined amount sufficient to form a liquidfilm covering the whole area of a principal face of the substrate;forming the liquid film covering the whole area of the principal face ofthe substrate by supplying process liquid reserved by the process liquidreservoir toward the principal face of the substrate being rotated;wherein the liquid film forming step includes the steps of supplyingpressurized gas to pressurize said process liquid reservoir and thenusing said pressurized gas to push out the process liquid reserved inthe process liquid reservoir, and thereby supply said process liquid tosaid substrate in a single burst; and after the liquid film formingstep, dispensing the process liquid from a process liquid nozzle towardthe principal face of the substrate being rotated.
 2. The substrateprocessing method according to claim 1, wherein the substrate rotatingstep includes the steps of: first, rotating the substrate at a firstrotational speed in parallel with the liquid film forming process; andsecond, rotating the substrate at a second rotational speed that isslower than the first rotational speed in parallel with the dispensingstep.
 3. The substrate processing method according to claim 1, whereinthe process liquid reservoir includes a first process liquid reservoirfor reserving a first process liquid and a second process liquidreservoir for reserving a second process liquid, and the liquid filmforming process includes the steps of: releasing the first processliquid from the first process liquid reservoir in a single burst,releasing the second process liquid from the second process liquidreservoir in a single burst, and supplying the first and second processliquid onto the principal face of the substrate while being mixedtogether.
 4. The substrate processing method according to claim 1,wherein the liquid film forming process includes the step of releasingthe process liquid reserved in the process liquid reservoir at a processliquid releasing position that is positioned above the principal face ofthe substrate being rotated.
 5. The substrate processing methodaccording to claim 4, wherein the reserving step includes the step ofsupplying the process liquid dispensed from the process liquid nozzleinto the process liquid reservoir by disposing the process liquidreservoir at a retreat position that is retreated from a position abovethe principal face of the substrate.
 6. The substrate processing methodaccording to claim 1, further comprising the step of recovering a usedprocess liquid that has been supplied from the process liquid nozzletoward the substrate and used for processing, and guiding the usedprocess liquid into the process liquid reservoir.
 7. The substrateprocessing method according to claim 1, wherein the whole quantity ofthe process liquid reserved in the process liquid reservoir is pushedout toward the substrate in said single burst.
 8. The substrateprocessing method according to claim 1, wherein said process liquidreservoir is hermetically closed.
 9. The substrate processing methodaccording to claim 8, wherein a valve is disposed in a pipe that carriessaid process liquid from said process liquid reservoir to saidsubstrate; and after said pressurized gas has been supplied to saidreservoir, said valve is opened to thereby supply said process liquid tosaid substrate in the single burst.
 10. The substrate processing methodaccording to claim 1, wherein a valve is disposed in a pipe that carriessaid process liquid from said process liquid reservoir to saidsubstrate; and after said pressurized gas has been supplied to saidreservoir, said valve is opened to thereby supply said process liquid tosaid substrate in the single burst.
 11. The substrate processing methodaccording to claim 1, wherein said single burst supplies 30-70 cc ofprocess liquid to said substrate within about 2 seconds.